Time Domian Electron Paramagnetic Resonance Imaging

时域电子顺磁共振成像

• 批准号: 7592717
• 负责人: murali cherukuri
• 金额: $ 105.09万
• 依托单位: DIVISION OF BASIC SCIENCES - NCI
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/7592717
• 关键词: 3-Dimensional; Air; Algorithms; Amplifiers; Anatomy; Anesthesia procedures; Animal Housing; Animals; Blood Volume; Blood flow; Body Temperature; Cellularity; Client; Collection; Computer software; Custom; Data; Data Set; Electron Spin Resonance Spectroscopy; Electronics; Engineering; Frequencies; Goals; Hour; Hypoxia; Image; Invasive; Life; Linux; Location; Magnetic Resonance Imaging; Magnetic Resonance Spectroscopy; Maps; Measures; Memory; Modality; Molecular; Mus; Nuclear; Occupations; Operative Surgical Procedures; Output; Oxygen; Oxygen saturation measurement; Performance; Physiologic pulse; Physiological; Physiology; Process; Prognostic Factor; Pulse taking; Purpose; RF coil; Radiation therapy; Range; Resolution; Running; Secure; System; Techniques; Technology; Testing; Time; Tissues; Tracer; Width; base; blood perfusion; cost; data acquisition; design; graphical user interface; image reconstruction; in vivo; indexing; instrumentation; nanosecond; novel; novel strategies; programs; radiofrequency; research study; size; treatment planning; tumor; water diffusion

Project 1: Time Domian Electron Paramagnetic Resonance Imaging: Instrumentation: Programmable Timing Unit: The time resolution of the radiofrequency pulses needed in EPR Imaging at any given frequency requires time resolution in nanosecond range unlike MRI experiments at the same frequency. This is because of the faster spin dynamics of paramagnetic spin systems compared to nuclear spin dynamics. The timing unit to manage the RF circuitry is not available commercially. We have designed, tested, and integrated a novel programmable timing unit with nanosecond time resolution which controls all the RF modules in the spectrometer using a new approach in RF electronics utilizing LabView technology. Integrating this unit resulted in simplifying the spectrometer operation significantly so that general purpose users can use the scanner without RF engineering expertise. In addition, this addition to the spectrometer made the unit less bulky and decreased the cost of the second spectrometer being built for the newly purchased open magnet system. Open Magnet System: The currently used magnet for all the studies was purchased in 1994 and has provided reliable performance. However, the small bore size and design makes in vivo experiments difficult in terms of housing the animal and have the anesthesia, iv lines etc and the air handling in the bore to maintain the core body temperature at 37 C. To overcome these difficulties, we have procured and installed an open magnet system with access in both directions in the horizontal plane (X- and Y-directions) so that in vivo experiments can be performed with ease. The magnet and gradient coils have been calibrated with the corresponding amplifiers and the control software completed. The RF chain is integrated and the system is ready for operation. Gantry for EPRI-MRI combined imaging: Since EPR based pO2 images lack anatomic information, interpreting the oxygen maps is often equivocal. To overcome this limitation, we have developed strategies for co-registering the EPR Images with anatomic images from MRI. The frequency of operation in EPRI of 300 MHz is similar to that of an MRI scanner operating at 7 T. Therefore a common resonator and gantry were designed, tested, optimized for operation in both modalities and used for sequential imaging of the object with EPRI and RI without moving the object. This made it possible to interpret the oxygen maps more reliable utilizing the anatomic guidance. In Vivo EPRI and MRI Co-Imaging: EPR imaging can visualize the distribution of oxygen concentration in tumor, though it doesnt provide anatomical information. The combined system of EPRI/MRI makes it possible to know the exact location of hypoxic core in the tumor anatomy, and also multi-functional analysis of tumor physiology combining the oxygen status and other functions by MRI including blood volume, blood flow, water diffusion etc. 300 MHz pulsed EPR/oxygen imaging system was constructed in which the RF coil and gantry were designed to also be used for MRI. The mouse to be measured is transferred between EPR and MRI magnets without removing the mouse from the coil, making reliable and simple co-registration of oxygen map by EPRI and anatomy by MRI possible. Using this EPR/MRI co-registration system, the relationship among tumor oxygen status, other parameters including blood perfusion, water diffusion which inversely related with tumor cellularity, MR spectroscopy, and resulting output of radiation therapy is underway. Image Reconstruction: The currently used EPRI image reconstruction algorithms are adapted on a Pentium PC. The current situation is that the data sets are to calculate the pO2 images with the required spatial and physiological resolutions. It takes 2 hours computational time to reorganize the acquired data and an additional 30 minutes to calculate the pO2 values in each voxel. This imposes enormous burden to process routinely collected image data from in vivo experiments. To reduce the image reconstruction time, we have acquired a Linux-based four dual-core cluster CPU with a 2 TB memory. Currently, whenever the phantom/animal in-vivo oximetry experiment is completed, the 3-D oximetry data sets that are collected in the collection machine are transferred to the Parallel Server via network I/O. A unique index file is created during every experiment and used by the server to construct PBS (Parallel Batch Server) job. The FIDs are reduced by automatically running a multi-threaded C program by the four dual-core processors of the machine. A graphical user interface (GUI) developed using custom parallel Matlab, uses the reduced data sets to view the mesh plots and to reconstruct the concentration images and oxygen images depending upon the input parameters provided by the user. The time complexity has now drastically reduced in the order of few minutes. A Windows PC client to Linux server connection via Samba (Session Message Block) connectivity and SSH (Secure Shell) enables any authorized users to run the GUI

项目1：时间域电子顺磁共振成像：仪器：可编程计时单元：EPR成像所需的射频脉冲在任何给定频率下的时间分辨率需要纳秒范围内的时间分辨率，而不同于相同频率下的MRI实验。这是因为与核自旋动力学相比，顺磁自旋系统的自旋动力学更快。用于管理RF电路的定时单元在商业上是买不到的。我们设计、测试和集成了一种新型的具有纳秒时间分辨率的可编程定时单元，它使用一种利用LabVIEW技术的射频电子学的新方法来控制光谱仪中的所有射频模块。集成该单元大大简化了光谱仪的操作，使普通用户无需具备射频工程专业知识即可使用该扫描仪。此外，光谱仪的这一补充使该装置体积更小，并降低了为新购买的开放磁体系统建造的第二台光谱仪的成本。开放式磁铁系统：目前用于所有研究的磁铁是在1994年购买的，性能可靠。然而，小孔的尺寸和设计使得活体实验在容纳动物方面变得困难，并且有麻醉、静脉输液管路等和孔中的空气处理以将核心体温保持在37℃。为了克服这些困难，我们购买并安装了在水平面(X方向和Y方向)具有双向通道的开放式磁铁系统，以便可以轻松地进行体内实验。对磁体线圈和梯度线圈进行了标定，并完成了相应的放大器和控制软件的编制。射频链已集成，系统已准备好投入运行。EPRI-MRI联合成像的机架：由于基于EPR的PO2图像缺乏解剖信息，因此对氧图的解释通常是模棱两可的。为了克服这一限制，我们开发了EPR图像与来自MRI的解剖图像的联合配准策略。在300 MHz的EPRI中的操作频率与在7T下操作的MRI扫描仪的频率相似。因此，设计、测试和优化了公共谐振器和机架，用于在不移动对象的情况下使用EPRI和RI对对象进行顺序成像。这使得利用解剖引导更可靠地解释氧图成为可能。在活体EPRI和MRI联合成像中：EPR成像可以可视化肿瘤内的氧浓度分布，尽管它不提供解剖学信息。EPRI/MRI的组合系统使人们能够准确地了解肿瘤解剖中缺氧核心的位置，并结合MRI的氧状态和其他功能(包括血容量、血流量、水扩散等)对肿瘤生理进行多功能分析。被测量的小鼠在EPR和MRI磁铁之间转移，而不需要将鼠标从线圈中取出，从而使EPRI的氧图和MRI的解剖可靠而简单地共同配准成为可能。利用这一EPR/MRI联合配准系统，正在进行肿瘤氧状态、其他参数(包括血液灌注量、与肿瘤细胞密度负相关的水扩散)、磁共振波谱以及放射治疗结果之间的关系。图像重建：目前使用的EPRI图像重建算法是在奔腾PC上改编的。目前的情况是，数据集要计算具有所需空间和生理分辨率的pO2图像。重组采集的数据需要2小时的计算时间，计算每个体素中的pO2值需要额外的30分钟。这给处理从活体实验中常规收集的图像数据带来了巨大的负担。为了减少图像重建时间，我们获得了一个基于Linux的四核集群CPU，内存为2TB。目前，每当体模/动物体内血氧测量实验完成后，采集机采集的三维血氧数据集通过网络I/O传输到并行服务器，在每次实验过程中创建一个唯一的索引文件，由服务器用来构建并行批处理服务器(PBS)作业。通过机器的四个双核处理器自动运行多线程C程序来减少FID。图形用户界面(图形用户界面)使用定制的并行MatLab开发，使用简化的数据集来查看网格图，并根据用户提供的输入参数重建浓度图像和氧气图像。时间复杂性现在已经大幅降低，只有几分钟的量级。Windows PC客户端通过Samba(会话消息块)连接和SSH(安全外壳)连接到Linux服务器，使任何授权用户都可以运行该图形用户界面